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CDPH Study Shows Prenatal Vaccination Decreases Severe Illness and Death in Pediatric Pertussis Cases  

Date: 10/23/2015 
Number: 15-079 
Contact: Anita Gore, Orville Thomas (916) 440 7259 

SACRAMENTO – California Department of Public Health (CDPH) Director and State Public Health Officer Dr. Karen Smith today announced the results of a CDPH study that shows additional benefits of prenatal pertussis vaccination. Vaccination of pregnant women against pertussis (whooping cough) has been found to prevent whooping cough in their infants, however no vaccine is 100 percent effective and some infants of vaccinated women develop pertussis.

The study found that infants were significantly less likely to have severe illness or die from pertussis if their mother had received the Tdap (tetanus, diphtheria and pertussis) vaccine during pregnancy.

“Prior studies have demonstrated that prenatal Tdap vaccination reduces the risk of whooping cough among infants less than two months of age,” Dr. Smith said. “However, this is the first study that CDPH is aware of that has evaluated the impact of Tdap vaccine during pregnancy on the outcomes of infants who do become infected with pertussis. This study provides more evidence that getting the Tdap vaccine is the best way for pregnant mothers to protect their babies from pertussis and its complications.” 

CDPH’s Immunization Branch conducted the study among 690 California infants younger than two months of age who had pertussis. The study showed that infants with whooping cough whose mothers received Tdap vaccine during pregnancy were less likely to be hospitalized or admitted to an intensive care unit. Researchers also found that infants whose mothers received Tdap vaccine during pregnancy had significantly shorter hospital stays when hospitalization was needed. In addition, there were no deaths among infants whose mothers were vaccinated with Tdap.

Pregnant women should receive the whooping cough vaccine at 27 weeks, the start of the third trimester of each pregnancy. When pregnant women are vaccinated, maternal antibodies are transferred to the fetus and help protect young infants until they are old enough to receive their own vaccination against pertussis. This is the only way to provide direct protection to infants.

Whooping cough continues to spread at above-normal levels in California following a major epidemic in 2014, when the number of reported cases was the highest seen since the 1950s. Disease rates and the risk of hospitalization and death are highest for infants younger than three months of age.  

Classic whooping cough in children and adults starts with a cough and runny nose for one-to-two weeks, followed by weeks to months of rapid coughing fits that sometimes end with a whooping sound and vomiting. Fever is rare. Symptoms of whooping cough vary by age and vaccination history. Infants often do not have typical whooping cough symptoms and may not appear to cough. Instead, they may have difficulty breathing, their face may turn purple, and they may even stop breathing.

CDPH is working closely with local health departments, schools, media outlets, and other partners to inform providers and the public about the importance of vaccination against whooping cough, especially for pregnant women during the third trimester of every pregnancy. CDPH also reminds parents that Tdap vaccination is a requirement for advancement into the 7th grade. Tdap vaccinations are widely available at doctors’ offices, clinics, and pharmacies. To find a vaccination clinic or pharmacy near you, visit the HealthMap Vaccine Finder website.

Pertussis data, including the number of cases in each county, can be found on the CDPH website.
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